1. Technical Field
The present invention relates to a quantum interference device, an atomic oscillator, an electronic apparatus, and a moving object.
2. Related Art
As oscillators having high-accuracy oscillation characteristics on a long-term basis, atomic oscillators that oscillate based on energy transition of atoms of alkali metals including rubidium and cesium are known.
Generally, the operation principle of the atomic oscillators is roughly classified into a system using a double resonance phenomenon by light and microwave and a system using a quantum interference effect (CPT: Coherent Population Trapping) by two kinds of lights having different wavelengths. The atomic oscillators using the quantum interference effect may be made smaller than the atomic oscillators using the double resonance phenomenon, and have been recently expected to be mounted on various apparatuses (for example, Patent Document 1 (JP-A-2013-125907)).
As disclosed in Patent Document 1, for example, the atomic oscillator using the quantum interference effect includes a gas cell in which a gaseous alkali metal is enclosed, a light source that outputs resonance light for resonance of the alkali metal in the gas cell, and a photodetector (light receiving unit) that detects the resonance light transmitted through the gas cell. Further, in the atomic oscillator, an electromagnetically induced transparency (EIT) phenomenon that, when the frequency difference between two kinds of resonance lights takes a specific value, none of the two kinds of resonance lights are absorbed by the alkali metal within the gas cell, but transmitted occurs, and an EIT signal as a steep signal generated with the EIT phenomenon is detected by the photodetector and the EIT signal is used as a reference signal.
However, in the atomic oscillator of Patent Document 1, a surface-emitting laser (VCSEL) that outputs lights in a single mode is used as the light source for resonation of the alkali metal. Accordingly, compared to a multimode surface-emitting laser that outputs lights in a plurality of modes, there are problems in structure that the drive voltage is higher, the resistance to electrostatic discharge damage is lower, and the life is shorter.